Ultraviolet (UV) liquid disinfection or treatment systems, using UV light source have been long known. The irradiation of the liquid inactivates treats and/or removes microorganisms and other types of contaminations in the liquid, if the irradiation intensity and exposure duration are above a minimum dose level. The UV dose may be measured in units of miliJoules per square centimeter delivered by the UV disinfection system to water to ensure disinfection to the required level. Commercial UV disinfection systems are designed to inactivate known microorganisms using a single type of UV lamps that emits UV light in the germicidal spectrum.
Recent regulations regarding the discharging of ballast water in harbors require the inactivation or removal of various sea water contaminations for example, microorganisms and marine species (ballast water are sea water held in a tank within a sea vessel that balances the vessel). For example, regulations were set by the International Maritime Organization (IMO) and the United States Coast Gourd (USCG) together with the US Environmental Production Agency (EPA). Ballast water pumped from the sea in a first ecosystem (a first harbor) may contain marine species typical for that ecosystem. Discharging the water at a second ecosystem (in a second harbor) may harm the marine environment in the second ecosystem introducing new unnatural species to that ecosystem. The new regulations were set to ensure that only a minimal amount of new species either, microorganisms (e.g., bacteria) or larger organisms (e.g., zooplankton) are discharge into the sea.
Water, either sea water, ballast water, brackish water or fresh water, to be treated and/or disinfected may contain several types of contaminations, for example organism, bacteria, microorganism, microbe, germ, virus, organic contaminator and non-organic contaminator. Each type of entity or contamination may be inactivated or removed after exposure to UV light having different spectra. For example, microorganisms such as Escherichia, coli and Vibrio may be inactivated at the germicidal UV spectrum (e.g., 200-300 nm). The germicidal spectrum is partially in the UVC (100-280 nm) spectrum and partially in the UVB (280-315 nm) spectrum. In yet another example, marine species such as Zooplankton and Phytoplankton may be more sensitive to UV light at the UVC spectrum. Absorption of UV light in organic pollutant such as chloramines and chlorides may cause the oxidation and/or disintegration of the organic pollutant. Each organic compound may have different absorption pick at different part of the UV spectrum. For example, NH2Cl absorbs UV light having a wavelength of 400, 423 and 414 nm at the UVA spectrum; NHCl2 absorbs UV light having a wavelength of 135, 112 and 110 nm at the UVC spectrum; and NCl2 absorbs UV light having a wavelength of 415, 450 and 462 also at the UVA spectrum.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the drawings have not necessarily been drawn accurately or to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements. Moreover, some of the blocks depicted in the drawings may be combined into a single function.